So as not to frighten people away with quotations from wild German professors, here's a good summary of the monetary theory of value from a New York-based business journalist.
Oh, and Happy New Year's to all.
"money and power
Several aspects of Marx’s theorizing on money and credit are worth savoring: the inseparability of money and commerce, the political nature of money (and the inseparability of market and state), and the role of credit in breaking capital’s own barriers to accumulation. Unlike mainstream economics, which has a hard time joining theories of money to theories of production, the two are inseparable in Marx. Production is always for profit, and exchange is always for money, and the existence of money presupposes and embodies the whole set of capitalist social relations. This is important not only in the strictly “economic” sense but as is always the case in Marx, also the broadly political sense as well. “The individual carries his social power, as well as his bond with society, in his pocket” (Marx 1973, p. 157). Words like “power” and “bond” are not seen in mainstream economics texts. Behind the illusions of the market as “a very Eden of the innate rights of man…the exclusive realm of Freedom, Equality, Property, and Bentham” (Marx 1977, p. 280) lie harsher realities. Money, far from being the neutral lubricant of classical theory, or the politically neutralizable one of Keynesian theory, is fundamentally about compulsion and command: capitalists who can’t turn their products into cash go under (or in these more indulgent days, file for reorganization), and workers who can’t turn their labor into cash will starve.
[...]
"In this deeply political role, as one of the fundamental mechanisms of social organization under capitalism, money and credit not only drive competition between capitals and force workers to work or die, they also regulate the affairs of whole governments and countries. Marx emphasized that despite the fantasies of libertarians, who dream of stateless monies like gold, money has to be guaranteed by a state, and credit supervised by one. Money is purely conventional; there’s nothing intrinsically magic about gold or Federal Reserve notes. The various forms of money are valuable because people agree they are, and some forceful monopolist — a central bank and a national Treasury — has to be the ultimate guarantor of agreement, or convention would dissolve"
Source: http://www.wallstreetthebook.com/